The present invention relates to an information-recording medium and method for recording and reproducing information by using light.
In the present application, media for recording and reproducing information, such as optical disks, are called “information-recording media”.
There are hitherto various optical disks such as DVD-RAM disks that use a phase-change film as an information-recording film, and CD-R and DVD-R disks that use organic materials as information layers. In the optical disks using organic materials as information layers, the information layer contains dyes absorbing a recording light, and so a substrate surface contacting with it is transformed by laser irradiation and information is recorded.
Conventionally, as disclosed in, for example, Japanese Patent Laid-open No. 63-122032, there has been known an electric field-effect optical disk in which information is recorded on a phase-change recording film by irradiation of a laser beam while an electric field is applied to the recording layer. These disks employ a device structure wherein a phase-change information layer containing, for example, GeSbTe etc. is sandwiched between upper and lower electrodes. This purpose is that phase change (crystallization) caused by laser-beam irradiation is further promoted by application of an electric field to the recording film.
Further, Japanese Patent Laid-open No. 5-101454 describes an optical information-recording medium in which a semiconductor film made from WO3 having a photo-intercalating or photo-deintercalating effect and an electrolyte film are disposed so as to contact with each other and which becomes transparent since ions in the electrolyte film are taken in an optical semiconductor when light is irradiated.